LONDON —
Britain announced Tuesday it will re-open its embassy in Iran, three years after it was closed following an attack on the building by Iranian protesters. The decision is the latest move by a Western nation to improve relations with Iran as the crisis in neighboring Iraq intensifies.

British Foreign Secretary William Hague made the announcement in parliament.

“We will be reopening our embassy in Tehran. Initially, this will be with a small diplomatic team. But it is an important step forward in our bilateral relations with Iran,” he said.

Hague said Iran will also likely reopen its embassy in London.

The foreign secretary said Britain would use the increased diplomatic contact in part to press Iran to end what he called “its support for sectarian groups.” That was an apparent reference to Iraq, where Iran supports the Shi'ite government and other groups that the West has accused of alienating Sunnis and fueling support for Sunni extremist groups.

One of those groups, the Islamic State in Iraq and the Levant, has taken control of several Iraqi cities during the past week, and has advanced to within 65 kilometers of Baghdad.

The crisis has put Iran in the spotlight, and got this comment on Yahoo! News from U.S. Secretary of State John Kerry.

“We're open to discussions if there's something constructive that can be contributed by Iran, if Iran is prepared to do something that is going to respect the integrity and sovereignty of Iraq and the ability of the government to reform,” said Kerry.

One result was a brief high-level meeting between senior U.S. and Iranian officials to discuss Iraq on Monday in Vienna, where the two countries are the key players in talks on the future of Iran’s nuclear program.

State Department spokeswoman Jen Psaki noted that U.S. officials have spoken with Iran on other issues in recent years, including the situation in Afghanistan. She characterized Monday’s meeting this way.

“We’re not talking about coordinating any military action in Iraq with Iran. We would encourage Iran to push the Iraqis to act to address problems in a nonsectarian way,” said Psaki.

But that has not been Iran’s policy so far. It supported militant Shi'ite groups fighting U.S. and other international forces during Iraq’s civil war. More recently, Iran has backed the increasingly sectarian Shi'ite Iraqi government.

At the Maplecroft risk assessment firm, analyst Torbjorn Soltvedt says the U.S. and British approaches to Iran show how concerned they are about the advance of the Sunni militants in Iraq. But he says it carries considerable risks.

“You could envision a situation where Sunni civilian populations could be killed in attacks carried out either by militias backed by Iran or even by Revolutionary Guard forces themselves. In that kind of scenario, then the already bad sectarian tensions in Iraq could get even worse,” said Soltvedt.

U.S. and British officials have stressed that they will urge Iran to take the opposite course, and push their Iraqi allies to moderate their sectarian tendencies.

But it is not clear whether Iran sees that as being in its interest. Some analysts warn Iran might prefer the breakup of Iraq, with a militant Sunni entity in the west, the Kurdish enclave in the north, and a weakened government in Baghdad struggling to control the rest of the country.